A good place for valves is RS - a bit pricey but good quality.

I have made my own regulator based on the palmer design and it gives such a good flow rate that I do not need a buffer tank, I am not sure whether a palmer reg could be modified to my spec. I dismantled a standard ram and fitted a spring inside to retract the flipper.

The main valve is of my own design but prior to that I used a 20bar 24v solenoid 2/2 valve(technobots) and a drilled hole in the ram feed to vent. This set up was capable of turning over any other machine, and if fired without a robot on top it would land me on my a**e.

I will put an image of the machine self-righting on my profile.

Feel free to e-mail me if you want to know more.